前端请求：

http://localhost:3002/api/user/login?username=002&password=002

后端响应

router.get('/api/user/login', (req, res) => {

    let username = req.query.username;
    let password = req.query.password;
    const sqlStr = `SELECT * FROM sys_user where username= '${username}' and password='${password}'`
    console.log(sqlStr)
    db.query(sqlStr, (err, results) => {
        // 查询数据失败
        if (err) {
            return console.log(err.message)
        } else {
            res.send({
                status: 200,
                message: '获取所有用户成功',
                data: results,
            })
        }
    })

})

结论：使用req.query.参数名 获取参数值

执行效果